In the mining and milling of gold bearing ore, there are known machines which are used for impaction of the ore particles in a dry state.
These machines are basically drums into which the gold bearing ore is deposited. The drums have internally a plurality of rotor discs and hammers which are rotated at approximately 1000-1500 rpm, forcing the ore onto a series of plate members formed on the inside of the drum wall. The rotational speed of the rotor ensures that the ore particles are impacted at great speed. The different particles in the ore once broken down are able to be concentrated wherein the gold particles are concentrated at the bottom of the machine whilst the lighter materials are discharged.